This shock-absorbing member is equipped with a tubular body comprising a plurality of flat plate parts and a plurality of corner parts provided between the plurality of flat plate parts, said shocking-absorbing member having a cross-sectional shape perpendicular to the longitudinal direction that is polygonal. A heat-treated part that has been heat-treated by means of laser light and has been deformed by 0.1 to 3.0 degrees is formed on at least one of the plurality of flat plate parts.